US4788771A - Cord cutter head having a noncircular cross section - Google Patents

Cord cutter head having a noncircular cross section Download PDF

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Publication number
US4788771A
US4788771A US07/053,024 US5302487A US4788771A US 4788771 A US4788771 A US 4788771A US 5302487 A US5302487 A US 5302487A US 4788771 A US4788771 A US 4788771A
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US
United States
Prior art keywords
spool
cord
cutter
housing
cutter head
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
US07/053,024
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English (en)
Inventor
Toru Baba
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kioritz Corp
Original Assignee
Kioritz Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kioritz Corp filed Critical Kioritz Corp
Assigned to KIORITZ CORPORATION reassignment KIORITZ CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: BABA, TORU
Application granted granted Critical
Publication of US4788771A publication Critical patent/US4788771A/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01D—HARVESTING; MOWING
    • A01D34/00—Mowers; Mowing apparatus of harvesters
    • A01D34/01—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus
    • A01D34/412—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus having rotating cutters
    • A01D34/416—Flexible line cutters

Definitions

  • the present invention relates to a cord cutter head for use in, for example, a grass trimmer.
  • a cutter head has a flexible cord made of a plastic such as nylon and adapted to serve as a cutter blade.
  • the cord cutter head also has a housing fixed to one end of a drive shaft, and a spool accommodated by the housing and carrying the cutter cord wound thereon. In operation, the free end of the cutter cord is extracted by a desired length.
  • the drive shaft is drivingly connected to a suitable power source such as a small-sized internal combustion engine, through a suitable transmission.
  • iner When the cutter cord outside the housing has been worn out or cut accidentally, it is necessary to extract a new portion of the cutter cord from the housing. Hithereto, the extraction of the new portion of the cutter head is conducted semi-automatically by means of, for example, a device generally referred to as "inertia shifter".
  • Such a conventional cord cutter head suffers from a disadvantage in that the construction is complicated and the size is increased with a result that the weight and the cost are increased undesirably.
  • handling and operations, as well as repair and maintenance, are generally difficult to conduct.
  • an object of the present invention is to provide a cord cutter head which is simplified in construction and which is easy to handle and operate, thereby overcoming the above-described problems of the prior art.
  • a cord cutter head comprising: a housing having a downward opening, a spool mounted substantially in the center of the housing and carrying a flexible cutter cord wound thereon; and an aperture formed in the wall of the housing and adapted to allow the portion of the cutter cord unwound from the spool to pass therethrough; wherein the cross-sectional shape of the spool has a longer axis and a shorter axis.
  • the user can easily wind the cord on the spool or unwind the cord from the spool. Namely, since the spool portion exposed from the housing has a cross-section with longer and shorter axes, the user can unwind and extract new portion of the cord by his fingers. In consequence, the number of the parts employed is decreased to simplify the construction and to facilitate handling and operation, as well as repair and maintenance. For the same reasons, the cost of the cord cutter head is reduced advantageously.
  • the cutter cord can effectively be protected by suitable selection of positions of the aperture and the spool. It will also be possible to modify the design by, for example, constructing the spool, housing and large-diameter lower end portion of the spool separately, so as to increase the wear resistance according to the uses, thus accomplishing a further improvement.
  • FIG. 1 is a sectional side elevational view of an essential portion of an embodiment of the cord cutter in accordance with the present invention.
  • FIG. 2 is a cross-sectional view of an essential portion of the embodiment shown in FIG. 1.
  • a cord cutter head embodying the present invention has a drive shaft 1 to which are integrally fixed a housing 2 and a spool 3.
  • the drive shaft 1 is connected to a small-sized internal combustion engine through a suitable transmission means (not shown) which may be a flexible shaft.
  • the drive shaft 1 when driven by the engine, drives the housing 2 and the spool 3 rotatingly as indicated by an arrow.
  • the spool 3 has a boss portion of a cross-section having a longer axis and a shorter axis as will be seen from FIG. 2.
  • a flexible cutter cord 4 made of a plastic material such as nylon is wound on the boss portion of the spool 3.
  • the free end of the flexible cutter cord 4 is extracted by a desired length to the outside of the housing 2 through an aperture 5 which is formed in a portion of the wall of the housing 2 adjacent to an extension of the shorter axis of cross-section of the spool 3.
  • the spool 3 is provided on the lower end thereof with an large-diameter portion 6 having a circular cross-section, so as to prevent the cutter cord 4 on the spool 3 from coming off the spool 3.
  • the housing 2, the spool 3 and the cutter cord 4 are driven at a high speed as a unit with the drive shaft 1, so that a centrifugal force acts on the free end portion of the cutter cord 4 extracted from the housing 2.
  • the free end portion of the cutter cord 4 is straightened so as to act as a bar which strikes and cuts the grass.
  • the cutter cord 4 which has passed through the aperture 5 is bent around the aperture 5 to the leading side as viewed in the direction of rotation, such that the portion of the cutter cord 4 emerging from the housing 2 makes an angle ⁇ to the extension of the portion of the cutter cord 4 between the aperture 5 and the spool 3, so that the centrifugal force acting on the cutter cord 4 is resisted and borne by the rigidity of the cutter cord 4.
  • the resisting force produced by the rigidity of the cutter cord 4 prevents the centrifugal force from directly acting on the spool 3. In consequence, problems such as welding or embedding of the cutter cord 4, which may otherwise be caused by the centrifugal force, are eliminated.
  • the aperture 5 is offset by an amount h from the center of the spool 3 to the trailing side as viewed in the direction of rotation of the cord cutter head.
  • the spool 3 shown in FIG. 2 has an elliptic cross-section, this cross-sectional shape is not exclusive and other cross-sectional shapes such as oval shape, cocoon-like shape and so forth, as well as a hollow cross-section, may be employed equally.
  • the spool 3 has a non-circular cross-section, for the purpose of increasing the effective spool diameter in the region where the cutter cord 4 leaves the spool 3 so as to protect the cord, while minimizing the length of the cutter cord unwound per each unwinding operation.
  • the non-circular cross-section of the spool 3 provides a greater distance between the aperture 5 and the portion of the spool 3 at which the cord leaves the spool 3, which in turn facilitates the unwinding of the cutter cord 4 from the spool 3 by the user's fingers.
  • an extraction angle ⁇ which is not smaller than 90° but not greater than 120° is formed between the longer axis of the spool 3 and the portion of the cutter cord 4 extending between the spool 3 and the aperture 5.
  • the extraction angle may be selected to fall within the range of between 60° and 90°, without impairing the effect produced by the invention provided that a space ample enough to allow the manual work is obtained. It is thus possible to effectively protect the cutter cord 4 by limiting the direction of the longer axis of the cross-section of the spool 3 with respect to the aperture 5 formed in the wall of the housing 2.

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  • Life Sciences & Earth Sciences (AREA)
  • Environmental Sciences (AREA)
  • Harvester Elements (AREA)
US07/053,024 1986-05-24 1987-05-20 Cord cutter head having a noncircular cross section Expired - Fee Related US4788771A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP61-78615[U] 1986-05-24
JP1986078615U JPH0228676Y2 (ja) 1986-05-24 1986-05-24

Publications (1)

Publication Number Publication Date
US4788771A true US4788771A (en) 1988-12-06

Family

ID=13666790

Family Applications (1)

Application Number Title Priority Date Filing Date
US07/053,024 Expired - Fee Related US4788771A (en) 1986-05-24 1987-05-20 Cord cutter head having a noncircular cross section

Country Status (2)

Country Link
US (1) US4788771A (ja)
JP (1) JPH0228676Y2 (ja)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101321453B (zh) * 2005-09-13 2012-03-07 法布里齐奥·阿尔内托利 具有切割线保护的割草机头
US20130283752A1 (en) * 2012-03-19 2013-10-31 Robert Bosch Gmbh Line trimmer

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4124938A (en) * 1976-12-03 1978-11-14 Weed Eater, Inc. Flexible string cutting device

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4124938A (en) * 1976-12-03 1978-11-14 Weed Eater, Inc. Flexible string cutting device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101321453B (zh) * 2005-09-13 2012-03-07 法布里齐奥·阿尔内托利 具有切割线保护的割草机头
US20130283752A1 (en) * 2012-03-19 2013-10-31 Robert Bosch Gmbh Line trimmer

Also Published As

Publication number Publication date
JPS62190422U (ja) 1987-12-03
JPH0228676Y2 (ja) 1990-08-01

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Legal Events

Date Code Title Description
AS Assignment

Owner name: KIORITZ CORPORATION, 5-1, SHIMORENJAKU-7-CHOME, MI

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:BABA, TORU;REEL/FRAME:004714/0871

Effective date: 19870515

Owner name: KIORITZ CORPORATION, JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:BABA, TORU;REEL/FRAME:004714/0871

Effective date: 19870515

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Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

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Year of fee payment: 4

FPAY Fee payment

Year of fee payment: 8

REMI Maintenance fee reminder mailed
LAPS Lapse for failure to pay maintenance fees
FP Lapsed due to failure to pay maintenance fee

Effective date: 20001206

STCH Information on status: patent discontinuation

Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362